memcpy Problem

ADePSP · Post by **ADePSP** » Sat Sep 30, 2006 1:14 am

I'm having some problems with the memcpy function in C... I have a pointer to a chunk of data and I simply want to copy 2 bytes from it into a short...

See the code snippit,

Code: Select all

char* ptrData;
unsigned short myShort;

ptrData = getData&#40;&#41;;

memcpy&#40;&#40;char*&#41;&myShort, ptrData, 2&#41;;

printf&#40;"ptrData = %d\n",&#40;unsigned short&#41;ptrData&#41;;
printf&#40;"myShort = %d\n",myShort&#41;;

You would expect the output values to be the same but they are not... What I get is,

ptrData = 23568
myShort = 36096

Can anyone see what i'm doing wrong and why myShort has the wrong number in it...?

weltall · Post by **weltall** » Sat Sep 30, 2006 1:33 am

first of all what is the declaration of getdata and why ptrdata is a char when you are using it to store a shorth?
second you can't do a simple myshort = *(unsigned short*)ptrdata (didn't test it :P)

ADePSP · Post by **ADePSP** » Sat Sep 30, 2006 3:32 am

weltall wrote:first of all what is the declaration of getdata and why ptrdata is a char when you are using it to store a shorth?
second you can't do a simple myshort = *(unsigned short*)ptrdata (didn't test it :P)

It's ok, I worked it out... I was displaying the pointer of prtData rather than the data it contained... The memcpy did work and was correct... It was other mistakes that led me to believe otherwise...

Thanks anyway...

weltall · Post by **weltall** » Sat Sep 30, 2006 3:56 am

you should still remove the memcpy call bacause it's an unnedded lost of resources (it's still a function call)